This invention relates to an electric arrangement for regulating the luminous intensity of at least one discharge lamp, the arrangement comprising an electric circuit having a first winding arranged to surround a core of magnetizable material. This winding is included in a circuit for feeding the lamp and the core further includes a second winding coupled magnetically to the first winding.
Such an arrangement is known from U.S. Pat. No. 4,180,764. This Patent discloses an arrangement having an electric circuit comprising a series arrangement of a transductor and a discharge lamp, this circuit being connected to an alternating voltage source. The ends of the second winding of the transductor (the control winding) are connected to a rectifying bridge which has one input connected through a variable impedance to the voltage source. By means of the variable impedance, the inductance of the transductor is influenced and the luminous intensity of the discharge lamp can be regulated.
A disadvantage of this arrangement is that the variable impedance is connected directly to the voltage source (such as an alternating voltage source with a voltage of 220 V), as a result of which comparatively high power losses occur in the arrangement. Moreover, the voltage present at the actuation device of the variable impedance may mean that risks are involved with manual contact thereof. Besides, the arrangement of the circuit is such that it is not suitable to regulate simultaneously the luminous intensity of a plurality of lamps. The circuit comprises such electrical components that it occupies a comparatively large space, which is also disadvantageous.